IOMM AGZ-5
AGZ 026B through 130B
97
Liquid Line Sight Glass
The refrigerant sight glasses should be observed periodically. (A weekly observation
should be adequate.) A clear glass of liquid indicates that there is subcooled refrigerant
charge in the system. Bubbling refrigerant in the sight glass, during stable run
conditions, indicates that the system can be short of refrigerant charge. Refrigerant gas
flashing in the sight glass could also indicate an excessive pressure drop in the liquid
line, possibly due to a clogged filter-drier or a restriction elsewhere in the liquid line.
See Table 45 for maximum allowable pressure drops. If subcooling is low, add charge
to clear the sight glass. If subcooling is normal (15 to 20 degrees F) and flashing is
visible in the sight glass, check the pressure drop across the filter-drier. Subcooling
should be checked at full load with 70
°
F (21.1
°
C) outdoor air temperature, stable
conditions, and all fans running.
An element inside the sight glass indicates the moisture condition corresponding to a
given element color. If the sight glass does not indicate a dry condition after about 12
hours of operation, the circuit should be pumped down and the filter-drier changed or
verify moisture content by performing an acid test on the compressor oil.
Preventive Maintenance Schedule
OPERATION WEEKLY
MONTHLY
(Note 1)
ANNUAL
(Note 2)
General
Complete unit log and review (Note 3)
X
Visually inspect unit for loose or damaged components
X
Inspect thermal insulation for integrity
X
Clean and paint as required
X
Electrical
Check terminals for tightness, tighten as necessary
X
Clean control panel interior
X
Visually inspect components for signs of overheating
X
Verify compressor heater operation
X
Test and calibrate equipment protection and operating controls
X
Megger compressor motor
*
X
Refrigeration
Leak test
X
Check sight glasses for clear flow
X
Check filter-drier pressure drop (see manual for spec)
X
Perform compressor vibration test
X
Acid test oil sample
X
Condenser (air-cooled)
Clean condenser coils (Note 4)
X
Check fan blades for tightness on shaft (Note 5)
X
Check fans for loose rivets and cracks
X
Check coil fins for damage
X
Notes:
1. Monthly operations include all weekly operations.
2. Annual (or spring start-up) operations includes all weekly and monthly operations.
3. Log readings can be taken daily for a higher level of unit observation.
4. Coil cleaning can be required more frequently in areas with a high level of airborne particles.
5. Be sure fan motors are electrically locked out.
* Never Megger motors while they are in a vacuum.
Summary of Contents for AGZ026BS
Page 103: ...IOMM AGZ 5 AGZ 026B through 130B 103...
Page 104: ...104 AGZ 026B through 130B IOMM AGZ 5...
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